CHEM 112 Lecture Notes - Lecture 26: Bond-Dissociation Energy, Jet Fuel, Municipal Solid Waste

25 views2 pages

amethystbee103

14 Nov 2018

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Spontaneous and non spontaneous processes explosives and fuels. Breaking bonds is endothermic: energy is needed to separate the atoms in a bond, previously we have seen that the bond enthalpy is the energy needed to break one mole of bonds in gaseous molecules under standard conditions. Forming bonds is an exothermic process: the same amount of energy is absorbed when a bond is broken, is released when a bond is made. How to figure out the energy changes: draw the lewis structures for the molecules involved, draw it for the final product too look at how many bonds have to be broken. Petroleum and natural gas: can be different things depending on how long the hydrocarbon chains within it are for example could be asphalt, jet fuel, gasoline. Ethanol: fermentation of sugar, added to gasoline, doesn"t vaporize easily in cold climate so bad for canada, good in warmer climate.

Related Questions

In the following reactionCH4+CH4 arrow CH3CH3+H2two C-H bonds are broken(bond energy =412 kj/mol) to form a new C-C bond(bond energy=348 kj/mol and a new H-H bond(bond energy=436 kj/mol). Estimate the enthalpy in this reaction. Is it endothermic or exothermic:Hint for exothermic reactions the combined energies of the new bonds should be larger than the combined energies of the broken bonds.Balanced the following unbalanced reaction and calculate its standard free energy change(under standard reactions). State whether the reaction is spontaneous or nonspontaneous under standard conditionsC2H5OH(l)+O2(g) arrow CO2(g)+H2O(l) C2H5OH(l) O2(g) CO2(g) H2O(l) deltaH kj/mol -277.7 0 -393.5 -285.8 deltaG kjmol -174.8 0 -394.4 -237.1

Average bond enthalpies are generally defined for gas-phase molecules. Many substances are liquids in their standard state. (Section 5.7) By using appropriate thermochemical data from Appendix C, calculate average bond enthalpies in the liquid state for the following bonds, and compare these values to the gas-phase values given in Table 8.4: (a) Br – Br, from Br₂(l); (b) C – Cl, from CCl₄(l); (c) O – O, from H₂O₂(l) (assume that the O – H bond enthalpy is the same as that in the gas phase). (d) Does the process of breaking bonds in the liquid as compared to the gas phase cost more energy? Explain the difference in the ∆H values between the two phases.

olivecrab121

CHEM 112 Lecture Notes - Lecture 26: Bond-Dissociation Energy, Jet Fuel, Municipal Solid Waste

Document Summary

Get access

Related textbook solutions

Chemistry: Structure and Properties

Basic Chemistry

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Principles of Chemistry Molecular Approach

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related Documents

CHEM 112 Lecture Notes - Lecture 3: Chemical Polarity, Valence Electron, Octet Rule

CHEM 112 Chapter Notes - Chapter 7.9, 19.1 - 19.4: Standard Molar Entropy, Gibbs Free Energy, Boltzmann Constant

CHEM 112 Chapter Notes - Chapter 7.1 - 7.8: Ath, Cron, Ethylene

Related Questions